COLUMBUS, Ohio  — The Ohio Environmental Protection Agency is taking public comments on a proposed statewide permit that would allow certain data center facilities — particularly those unable to connect to centralized sewer systems — to discharge cooling-related wastewater and stormwater directly into Ohio waterways.

The draft National Pollutant Discharge Elimination System (NPDES) general permit, numbered OHD000001, would be Ohio EPA’s first-time issuance of a general permit specifically for discharges from data center facilities and is proposed to run for five years, according to the agency’s fact sheet.

In the permit’s opening authorization language, Ohio EPA states it has determined that a “lowering of water quality” associated with granting coverage under the permit is “necessary to accommodate important social and economic development” in Ohio, citing the state’s antidegradation rule and noting that certain analyses are excluded for general permits.

What the permit would cover

Ohio EPA says the general permit is intended to cover both wastewater and stormwater from qualifying data center facilities, defined generally as establishments providing computer processing and data preparation services under SIC code 7374.

Eligible discharges listed in the draft permit include:

  • Once-through or recirculated cooling water, used to remove heat from facility operations;
  • Certain low-volume wastewaters, such as cooling tower blowdown, boiler blowdown, and air compressor condensate (with exclusions);
  • Stormwater associated with industrial activity, including runoff from areas such as generators, chemical storage, and loading/unloading areas.
     

Limits, monitoring, and reporting

For wastewater discharges, the draft permit sets numeric limits, including:

  • pH: minimum 6.5 and maximum 9.0;
  • Total filterable residue (total dissolved solids): 1,500 mg/L (monthly);
  • Total residual chlorine: 0.019 mg/L (maximum) and 0.011 mg/L (monthly);
  • Total residual oxidants: 0.0024 mg/L (maximum) and 0.00026 mg/L (monthly).

The permit also requires monitoring for items including temperature, flow, and certain pollutants such as oil and grease, with electronic discharge monitoring reports due by the 20th day of the following month.

For stormwater-only outfalls, the draft requires sampling during storm events and includes benchmark concentrations — not effluent limits — of 100 mg/L for total suspended solids and 10 mg/L for oil and grease.

What is not mentioned in the permit

Notably, the draft data-center discharge permit and accompanying fact sheet do not mention radiation or PFAS (“forever chemicals”) at all, instead focusing its limits and monitoring on conventional parameters such as pH, total dissolved solids (total filterable residue), residual chlorine, residual oxidants, temperature, oil and grease, and flow, with stormwater benchmarks for total suspended solids and oil and grease.

Who would not qualify

The draft permit lists multiple categories of discharges that would be ineligible for coverage, including facilities that discharge to groundwater, facilities that discharge to lakes other than Lake Erie, certain discharges near public water supply intakes, and wastewater with volatile organic compound concentrations above 100 µg/L (monthly average), among other restrictions.

How companies would get covered

Facilities seeking coverage would have to submit a Notice of Intent and would not be covered until they receive written notification from the Ohio EPA director that the discharge is authorized, according to both the draft permit and fact sheet.

Ohio EPA’s fact sheet also states applicants must pay a $200 processing fee.

Public comments on the draft permit are open now, with the comment period running through Jan. 16, 2026, according to the public notice information released with the draft materials.

Public comments can be submitted here.